Many of the latest commercial passenger aircraft utilize computer controlled cockpit CRT displays which provide both a numerical and map presentation to the pilot of aircraft navigational data. Cockpit displays which show the horizontal position of the aircraft relative to a selected path have been disclosed in Applicants' co-pending application Ser. No. 716,979, now U.S. Pat. No. 4,692,869, filed Mar. 28, 1985 and entitled "AIRCRAFT NAVIGATIONAL SYSTEMS AND METHODS FOR CREATING NAVIGATIONAL GUIDE POINTS". Furthermore, Applicants have also disclosed a cockpit display which shows the position of the aircraft relative to a selected descent profile in their co-pending application Ser. No. 811,283 filed December 20, 1985 and entitled "AIRCRAFT DESCENT GUIDE SYSTEM AND METHOD FOR CREATING DESCENT GUIDANCE INFORMATION". An area navigation system for displaying aircraft position with reference to a selected horizontal path was disclosed in U.S. Pat. No. 4,086,632 by Lions, and which was assigned to the Assignee of the present invention.
Navigation systems for generating vertical navigational information have also been disclosed. For example, in U.S. Pat. No. 4,012,626 by Miller et al there is disclosed an area navigation system for generating pitch command signals for controlling the vertical flight path of an aircraft.
In addition, Baker et al.,in U.S. Pat. No. 4,021,009 discloses an area navigation system which generates flight path angle data for display at a cockpit vertical deviation indicator.